07/10/2018

Scientists Champion Forests As 'Unsung Hero' Of Climate Action

Reuters - Megan Rowling

BARCELONA - Scientists from around the world called for stepped-up efforts to use forests to keep global warming to the lowest limit agreed by governments in 2015, as a key report on how to meet that goal is finalised in South Korea this week.
“Forests really are the unsung hero of our struggle to address climate change,” said Deborah Lawrence, a University of Virginia professor and one of 40 scientists who backed a statement emphasizing how the Earth’s climate depends on forests.
The natural processes by which forests suck in and store carbon help reduce levels of planet-warming carbon dioxide in the atmosphere - and forests also underpin key parts of the world’s economy, the scientists said.
"Our planet's future climate is inextricably tied to the future of its forests," the international panel said. Credit: Fairfax Media
Yet humans have let forests become degraded, even as the resulting risks of disaster and the costs of repairing the damage rise, they added.
“We must protect and maintain healthy forests to avoid dangerous climate change and to ensure the world’s forests continue to provide services critical for the well-being of the planet and ourselves,” said the statement, signed by researchers mainly from the United States, Brazil and Europe.
“Our planet’s future climate is inextricably tied to the future of its forests,” they concluded.
The flagship report from the Intergovernmental Panel on Climate Change (IPCC), due to be published on Monday, will outline ways of limiting global temperature rise to 1.5 degrees Celsius (2.7 degrees Fahrenheit) compared with pre-industrial times, the most ambitious goal in the Paris climate pact.
One key route is to protect virgin forests, restore those that have suffered logging, fires or other harm, and expand the amount of land covered by trees, the report is expected to say.
In this week’s statement, scientists noted that forests remove about a quarter of the carbon dioxide humans add to the atmosphere, keeping climate change from getting even worse.
Destroying forests not only releases the carbon they contain but also eliminates their ability to take carbon dioxide out of the atmosphere, the statement said.
It noted that the world’s forests contain more carbon than exploitable oil, gas and coal deposits.
But deforestation rates are rising again in most of the tropics, due to expanded production of commodities such as palm oil, beef and grains, said Carlos Nobre, a University of Sao Paulo professor and member of the Brazilian Academy of Sciences.
Forests produce water vapor, boost rainfall and cool down local temperatures by as much as 3 degrees Celsius, Nobre noted.
“This is a critical element for growing food,” he said. “By keeping a wetter climate throughout the year, (forests) also mitigate the impacts of drought and are less vulnerable to fires.”

Diets matter
Scientists and environmental campaigners said policy makers often overlook the importance of forests in regulating the climate, meaning forest protection had received far too little funding.
But as the urgency of curbing rising temperatures increases, that is starting to change, they added, with attention shifting not just to forests but also to how land is deployed to produce crops for food and energy.
“There is a greater recognition in society as a whole that the land-use sector makes a difference - and the way that happens in people’s everyday lives is what they eat,” said Jennifer Morgan, executive director of Greenpeace International.
More people now understand the need to consume less meat and dairy products, she told reporters.
That is one strategy recommended in a separate report to be published in mid-October by the Climate, Land, Ambition and Rights Alliance (CLARA), a coalition of environment and development groups.
Its main findings, released this week, show greater efforts to move to more sustainable food systems, restore forests and secure land rights for local people can help limit global warming to 1.5 degrees Celsius.
The measures proposed - ranging from planting more trees on farms to feeding animals with agricultural leftovers and restoring major areas of forest - would cut emissions by 21 gigatonnes of carbon dioxide-equivalent per year by 2050, or about two-fifths of total greenhouse gas emissions in 2016.
The alliance said that would eliminate the need for largely untested technologies to remove carbon from the atmosphere.
Those methods include growing trees and crops to produce energy and then capturing and storing underground the carbon dioxide they release when harvested, an approach known as BECCS.
Kate Dooley of the University of Melbourne’s Climate and Energy College, and the main author of the CLARA report, said scientific models show BECCS would require a huge amount of land to be effective in meeting temperature limits, which would be “problematic”.
Opponents of BECCS argue it would take away land and water needed to end hunger and meet other global development goals, and could lead to abuses of indigenous land rights, among other risks.
“We can achieve the 1.5C pathways in the IPCC report - the safest pathways - through natural (land) sink enhancement,” Dooley told the Thomson Reuters Foundation.

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Earth's Climate Monsters Could Be Unleashed As Temperatures Rise

The Guardian - 

As a UN panel prepares a report on 1.5C global warming, researchers warn of the risks of ignoring ‘feedback’ effects
Fundamental questions are being raised about the ability of governments to stop the Earth from spiralling into a ‘hothouse’. Photograph: Peter van der Sleen/University o/PA 
This week, hundreds of scientists and government officials from more than 190 countries have been buzzing around a convention centre in the South Korean city of Incheon.
They are trying to agree on the first official release of a report – the bit called the Summary for Policymakers – that pulls together all of what’s known about how the world might be affected once global warming gets to 1.5C.
What will happen to coral reefs? How will extreme weather events and droughts change? What about heatwaves? And then, what are the different “pathways” that economies could choose to keep temperatures to 1.5C?
On Monday morning, the summary document is expected to be released, and there will be a cascade of headlines around the world.
The report, being pulled together by the United Nations Intergovernmental Panel on Climate Change, was one tiny part of the Paris climate change agreement.
As things stand, if you add up all the things that the 190-plus countries have committed to do as part of that Paris deal, global temperatures will probably go well above 3C.
We’re already at 1C of warming, so the extra half a degree isn’t far away – many scientists will say it’s already locked in, while others say there are plausible ways to stabilise temperatures at that level.
But in August, one of the world’s leading scientific journals – the Proceedings of the National Academy of Sciences – published a “perspective” article that has become known as the “hothouse earth” paper.
There was no new science in the paper and while it was speculative, it did raise fundamental questions about the ability of governments around the world to stop the Earth from spiralling into a “hothouse”.
I think the dominant linear, deterministic framework for assessing climate change is flawed
Will Steffen
One of the report’s authors, Professor Will Steffen, of Australian National University and the Stockholm Resilience Centre, talked me through it.
The problem lies with “feedbacks” – in the “supplementary information” attached to the paper, Steffen and colleagues actually listed 10 of them. With each, they include estimates of how much extra CO2 and temperature they could add once you hit about 2C of global warming.
For example, the ability of the land and ocean to keep soaking up CO2 could weaken, giving you an extra 0.25C of warming. Dieback of trees in the Amazon and subarctic could give us another 0.1C.
Permafrost, which is already starting to defy its name by not being all that permanent, could release ever more methane and carbon that might add a bit more warming again (0.09C is the estimate there).
The point is that once you add them all up, you get close to 0.5C of warming by the end of the century. Given we’re already at 1C of global warming, that makes the job of keeping warming “well below 2C” or even holding it at 1.5C much, much harder than it already is.
And there’s the rub.
While governments have the means to affect how much CO2 gets released through policies that radically cut the use of fossil fuels, it would be much harder to get a grip on thawing permafrosts, mass forest collapses or the loss of polar sea ice.
By failing to get a grip on a thing that’s feasibly under your control, we end up risking the release a whole gang of other monsters that we can’t.
This gets us to another big issue, says Steffen, because climate models don’t include some of these feedbacks. In essence, the warmer things get, the less reliable the models become. He tells me:
“I think the dominant linear, deterministic framework for assessing climate change is flawed, especially at higher levels of temperature rise.
So, yes, model projections using models that don’t include these processes indeed become less useful at higher temperature levels. Or, as my co-author John Schellnhuber says, we are making a big mistake when we think we can “park” the Earth System at any given temperature rise – say 2C – and expect it to stay there.”
For those who understand the idea of a carbon budget – where scientists have calculated how much CO2 you could emit before hitting certain temperature rises – it looks even meaner than before if Steffen and his colleagues are right.
But as they also point out, several of these feedbacks might have “tipping points” that then set off a cascade of other issues. Steffen says:
“Even at the current level of warming of about 1C above pre-industrial, we may have already crossed a tipping point for one of the feedback processes (Arctic summer sea ice), and we see instabilities in others – permafrost melting, Amazon forest dieback, boreal forest dieback and weakening of land and ocean physiological carbon sinks.
And we emphasise that these processes are not linear and often have built-in feedback processes that generate tipping point behaviour. For example, for melting permafrost, the chemical process that decomposes the peat generates heat itself, which leads to further melting and so on.”
For the record, Steffen thinks the assumptions in climate models that cuts in fossil fuel emissions will deliver relative cuts in temperatures “is OK for perhaps lower temperature rises of 1.5 or 2C” but beyond that, he’s sceptical.
The paper has received a bit of pushback from scientists, largely, it appears, because of the sensational headlines it attracted.
For example, Professor Richard Betts, of the UK’s MetOffice, has a measured perspective that’s well worth a look.
Dr Glen Peters, an Australian scientist and climate modeller based at the Centre for International Climate Research in Norway, also thought some of the media coverage went too far with the doomsday vibe.
But he told me that while it was true that many of the feedbacks in the paper were not well covered by climate models, this was partly because they were not that well understood. I’ll leave you with his thoughts:
“The hothouse earth paper conjectures that many of these feedbacks may interact like a domino effect, lead the Earth system to spiral out of control to reach a new steady state very different from today, and these processes may even start if we are successful at meeting the goals of the Paris Agreement.
“There is also an important timescale question, are we talking decades or millennia, and that is very important for how society may respond. While all the claims made in the hothouse earth paper are justified, we simply don’t have the data to verify if those claims are true. While the paper put in plenty of language to indicate its exploratory nature … many headlines and statements went too far, indicating we had already gone too far and there was no turning back.”
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From London To Shanghai, World's Sinking Cities Face Devastating Floods

The Guardian - 

Threat to major population centres is increasing as planners fail to prepare for impacts of global warming, report says
Flood victims in Bangkok, Thailand, in 2011. Like many other major cities across the globe, Bangkok is sinking – which puts it at increasing danger from sea level rises. Photograph: Paula Bronstein/Getty Images
London, Jakarta, Shanghai and Houston and other global cities that are already sinking will become increasingly vulnerable to storms and flooding as a result of global warming, campaigners have warned ahead of a landmark new report on climate science.
The threat to cities from sea level rises is increasing because city planners are failing to prepare, the charity Christian Aid said in the report. Some big cities are already subsiding – the ground beneath Shanghai, for instance, is being pressed down by the sheer weight of the buildings above – and rising sea levels resulting from global warming will make the effects worse.
The cities named in the report are sinking for a variety of reasons. Jakarta is thought to be subsiding by 25cm a year largely because of groundwater extraction, and Houston is sinking as the oil wells beneath it are depleted. Bangkok’s skyscrapers are weighing it down, while London is slowly sinking for geological reasons: Scotland is slowly rebounding after having been weighed down by glaciers during the last ice age, which is pushing southern England downwards like a see-saw.
The warning comes as the world’s leading climate scientists meet this week in South Korea to finalise a comprehensive study setting out whether and how the world can avoid temperature rises of 1.5C above pre-industrial levels. The Intergovernmental Panel on Climate Change (IPCC), the body of scientists convened by the UN, has been asked to examine the consequences of such a rise and assess what progress can be made to limit greenhouse gas emissions.
The world has already warmed by roughly 1C from pre-industrial levels, and sea levels could rise by 40cm if that increases to 1.5C, previous science from the IPCC has suggested. Sharp brakes on greenhouse gas production are expected to be needed to halt the rise.
Under the 2015 Paris agreement on climate change, governments pledged to hold warming to no more than 2C, with an aspiration not to surpass 1.5C, based on previous IPCC advice. The new IPCC report, to be published on Monday, is expected to show that remaining within the 1.5C limit is still possible but only with strong action to reduce carbon in the atmosphere.
Christian Aid, one of many organisations publishing studies to coincide with the IPCC’s judgment, looked at the consequences of a 1.5C rise for a selection of eight major cities around the world. The report concludes that poor development choices are exacerbating cities’ vulnerability to weather shocks.
Kat Kramer of Christian Aid, who wrote the report, said: “These global metropolises may look strong and stable, but it is a mirage. As sea levels rise, they are increasingly under threat and under water.”
Dozens of the world’s biggest cities are built in coastal areas and near major rivers, making them vulnerable not just to sea level rises but also to storm surges, which can send high seas inland and past maritime defences. The UK and the Netherlands experienced such a storm in 1953, when high tides and a storm surge inundated coastal regions. If similar weather were to strike today, the damage could be much greater despite sea defences, because of rising sea levels and the increased severity of storms that is likely to result from climate change.

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